Ceiling-mounted audio loudspeakers are well known in the art and have been commercially available for many years. Examples of such loudspeakers can be found in U.S. Pat. No. 5,088,574; U.S. Pat. No. 6,870,943; and U.S. Pat. No. 7,142,680, among other places. A ceiling loudspeaker is usually mounted in a hole that is cut in a ceiling structure, such as a ceiling tile, with the speaker being inserted through the hole and mounted to the tile or other plenum structure. The trend in interior design is for ceiling items, such as lighting fixtures, to be made smaller and less obtrusive, and ceiling-mounted loudspeakers are no exception to this. However, making a loudspeaker smaller generally involves a trade off in performance, usually involving the loss of bass frequencies, a reduction in speaker efficiency, or a combination of both, and as the size of the hole on the ceiling is reduced, the installation of an acoustic driver large enough to produce the desired level of output power has become a challenge for ceiling loudspeaker designers.
Another performance trade off in ceiling speakers is that, to keep the size small while retaining optimum frequency output, the system must use a coaxially mounted tweeter in tandem with a mid-bass driver. This presents two problems. The first is that a coaxially mounted tweeter suffers from the lack of a baffle, for if it is mounted on a bridge it is left hanging above the mid-bass driver. Alternatively, it can be mounted on a post, but still without a baffle. In such a structure, sound radiates from the tweeter to the mid-bass driver and then back out, causing frequency response anomalies in the far field. The second problem is that the mid-bass driver becomes “beamy” at the top of its working range; that is, its sound dispersion pattern is narrow so that as a listener moves off-axis from the driver, less upper midrange sound is heard. The tweeter cannot compensate for this because the low end of its range has been compromised by a lack of a proper baffle.
Thus, there is a need for an improved ceiling loudspeaker design which will avoid the foregoing trade-offs and will provide a loudspeaker that will fit in a reduced-diameter ceiling opening yet will provide the performance of a speaker larger than its apparent size.